Short Range Forecast Discussion NWS Weather Prediction Center College Park MD 315 PM EST Sun Jan 08 2017 Valid 00Z Mon Jan 09 2017 - 00Z Wed Jan 11 2017 ...Stormy conditions expected to persist over much of the western U.S... ...Arctic air in the eastern U.S. will give way to progressively milder air in the central U.S.... ...A winter storm is forecast to impact the upper Midwest and Great Lakes on Tuesday... Widespread rain and mountain snow are expected to persist across much of the western U.S. as an energetic upper-level pattern continues to direct moisture-laden low pressure systems from the Pacific into the West Coast. Northwestern California will be first in line to be impacted by rain, heavy at times, with the threat of flash flooding through Tuesday. Farther inland, snow will be widespread from the Sierras across the Great Basin, into the Intermountain region tonight, spreading to the north and east into the northern and central Rockies by tomorrow. In addition, some of the interior valleys will see freezing rain through tomorrow. The strong jet stream will continue to push the associated moisture eastward into the northern Plains on Monday, resulting in snow spreading rapidly into the Great Lakes by Monday night. By Tuesday, a reinforcing surge of arctic air from Canada will interact with the remnants of a Pacific front to trigger the formation a new low pressure system in the central U.S., which is expected to intensify and move rapidly into the Great Lakes by Tuesday evening. Thus, the potential exists for a significant winter storm to impact the upper Midwest to the upper Great Lakes on Tuesday with showers and thunderstorms extending farther south down the Ohio and Mississippi Valleys ahead of a cold front. Meanwhile, snow is also forecast for New England on Tuesday with widespread wintry precipitation possible farther southwest into Pennsylvania. Arctic air over the eastern U.S. is expected to retreat as high pressure system moves off the East Coast and much milder temperatures develop across the central U.S., where high temperatures is forecast to be more than 20 degrees above normal by Tuesday afternoon. Meanwhile, the next significant low pressure system is forecast to reach the West Coast later on Tuesday with a resurgent of heavy rains and mountain snows. Kong Graphics available at www.wpc.ncep.noaa.gov/basicwx/basicwx_ndfd.php